Prime Minister John Key appears uneasy about taking Murray McCully off the ballot paper in East Coast Bays in a bid to gift the seat to Conservative leader Colin Craig.

Mounting speculation about a deal to help the Craig into Parliament took a twist when NZ First leader Winston Peters revealed he might stand against Craig if National withdrew its candidate.

Asked about a deal, Key said he was close to making a decision, and wanted to do so before Parliament rose.

It may be announced next week together with other likely deals with ACT and UnitedFuture.

However, yesterday Key gave the strongest indication yet that he was reluctant to give Craig the kind of deal he wanted.

"Mr Craig has sort of indicated that if any accommodation was to be reached with him that that would require us not having Murray McCully on the ballot paper and I just think that's a very challenging thing to do because it relies on the fact that some other person doesn't put their name forward, either Winston Peters or somebody else."

Craig has called on Peters to "come clean and declare where he is standing".

Both NZ First and the Conservatives held annual conferences at the weekend and emerged at loggerheads after Peters hinted he planned to gatecrash any electorate deal the prime minister struck with Craig under which longtime East Coast Bays MP McCully would stand aside.Craig challenged Peters to make his intentions public.

"We have been upfront and transparent," Craig said.

"The prime minister has promised to do the same next week. Peters, on the other hand, is not being transparent and honest with New Zealand voters.

"Winston Peters should come clean and declare where he is standing, who he will work with, and what his bottom lines are.

"Voters deserve clarity so they may cast an informed vote, yet Peters is being deliberately slippery."

Peters has said he has been repeatedly approached about standing in East Coast Bays and he was seriously considering it.

"You've got political parties who think they can mess around with an electorate ... They might do that [but] they might be in for a surprise in one of them if they do pull that stunt," Peters said.

Craig, who on Saturday told the Conservative conference that he would not enter a coalition with National unless it signed up to binding referendums, was dismissive of Peters' warning.

"I think he did some similar sort of signalling last election, I think it's a game actually," Craig said.